The internet is a great democracy—for a large part, a free-for-all of content. Anyone can post almost anything they like, through blogs, other web pages, posted videos (e.g., on YouTube), with comments on pages of other users, and in numerous other ways. As a result, there is no end of information on the internet. But there is often a real dearth of high quality information, or the high quality information may be difficult to find among all the low quality content.
Although well known commercial writers, such as columnists for major newspapers, often generate some of the best written content, other rather unknown writers often can do just as well but are never recognized for their work. Using the internet, such writers can reach a gigantic audience, but they need to get noticed. Also, they need to make sure that other, malicious people, do not pretend to be them, and thus destroy their reputation.
Anonymity on the internet is easy, and makes for fabulous freedom of contribution (e.g., users have no fear of retribution for making honest comments). But it also makes it easy for any person of questionable background to pass themselves off as knowledgeable and then to amplify their viewpoint disproportionately, while making it difficult for those who are actually knowledgeable to provide proof of identity and credentials to correct fallacious information.
Authentication of users may take a variety of forms. For example, Facebook will generally trust that a user is a student at a university if the user has a currently valid e-mail address from the university. eBay tracks users via log in to keep records of how satisfied other are with the users' transactions, and Amazon.com uses so-called “Badges” for users. Merchants may require a credit card number and mailing address (or zip code) for the credit card bill along with a number printed on the back of the card. Other systems may use a challenge response protocol, such as by sending password information to an e-mail address that has previously been associated with a user. Other systems also permit a universal sign in, such as the various services available from GOOGLE. Moreover, systems like GOOGLE's WebmasterTools and SiteMaps permit webmasters to establish that they truly are associated with a site, by making them change the content of the site, and then checking to see that the content was changed in the prescribed manner.